1. Field of the Invention
The present invention relates to a communication device that allows a proxy reception device to perform proxy reception of data directed to the communication device, and relates to a control method for the communication device and a storage medium storing a program for executing the control method.
2. Description of the Related Art
As a protocol to establish a virtual session with a communication device connected to a network, a SIP (session initiation protocol) is stipulated in RFC 3261 and utilized for communication services such as IP (Internet protocol) telephone and IP-FAX.
To reduce power consumption, some communication device is configured to shift from a standby state to a sleep state upon elapse of a predetermined period of time in which the device remains in a non-operating state.
In IP-FAX, as with the case of conventional facsimile communication, a sender communication device originates a call, while specifying a receiver communication device as a destination. The receiver communication device, even if configured to shift to a sleep state, can immediately respond to an incoming call when it is in an operating state or in a standby state at the time of reception of the incoming call, but must be returned to the standby state when it is in the sleep state at that time.
Accordingly, there has been proposed a management device that transfers IP-FAX whose destination is a communication device which is in the sleep state to another communication device selected from among communication devices which are not in the sleep state, and allows the selected device to perform proxy reception (see, for example, Japanese Laid-open Patent Publication No. 2010-193359).
In the proposed management device, an identification information (e.g., device ID) of the communication device selected as the proxy reception device from among communication devices is registered into a SIP server. To this end, pieces of identification information of all the communication devices managed by the management device must be held in advance in the management device.
Instead of selecting the proxy reception device from among communication devices by the management device, it appears possible that a SIP URI (uniform resource identifier) of the communication device and an IP address of a destination (proxy reception device) to which a SIP session establishment request message (INVITE message) directed to the communication device is to be routed can be registered in association with each other into a SIP server by a communication device at the time of being shifted to the sleep state.
In that case, the INVITE message directed to the SIP URI of the communication device shifted to the sleep state is routed by the SIP server to the proxy reception device, and IP-FAX can be received by the proxy reception device, if the proxy reception device responds to the INVITE message and establishes a SIP session.
However, since the INVITE message is directed to a SIP URI other than that of the proxy reception device, the proxy reception device refuses to establish the SIP session. In other words, proxy reception of IP-FAX cannot be carried out by the technique where the communication device registers, into the SIP server, the destination to which the INVITE message directed to the communication device is to be routed.